<script>
    var shape = {
        width: 100,
        height: 100,
        get area() { 
            return this.width * this.height; 
        }
    };
    console.log(shape.width);
    console.log(shape["width"]);
    console.log(Reflect.get(shape, "width"));
    console.log(Reflect.get(shape,"area"));
    Reflect.set(shape,"height",200);  //设置shape对象中的height属性的值为200
    //调用shape对象中的属性area，并将this指向{width:5,height:8}
    console.log(Reflect.get(shape,"area",{width:5,height:8}));
</script>